This research is aimed at the synthesis of a number of new types of conjugated systems. The major emphasis is placed on the synthesis of stable derivatives of antiaromatic systems, in which the central ring system contains 4n pi electrons. Thus, we propose to make a number of derivatives of cyclopropenyl anion which will be stabilized by substituents, of cyclobutadiene, stabilized both by substitution and by ring fusion, and of cyclopentadienyl cation stabilized by suitable substituents. We also want to explore benzene dianions and benzene dication derivatives. Many of these compounds are predicted to have triplet ground states, and this may lead them to have quite unusual chemical and physical properties. In any case, we hope that these stabilized derivatives of fundamentally unstable systems will be attractive synthetic intermediates and that the properties of these compounds will help us to understand the quantum mechanical requirements for stability in conjugated systems.